WOW that is a nice cannon. How many cannons have you built before this one it looks really nice. It looks like you did you research on this, did you do design it by your self? Yay I spy no DWV on your cannon thumbs up . Welcome to the site and hope to see more good work from you.

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Coodude26 wrote:
People who laugh really hard at stuff that pisses you off/you getting hurt, who then say "I'm sorry, I can't stop" but you know they easily could.

Mr.C: That's not as easy as you think. It's like me kicking you in the balls and telling you to stop crying.

thanks, ive built so many ive lost count and Lowe's is always happy to have me in their pluming department

As for the design its mostly based on the materials i could get my hands on.The real beauty of the design is the extended tee that lets the piston travel father back opening a full 2inches and man this thing is powerful even at 30psi its got some kick!

To explain what Sticky_Tape means (S_T, don't post such useless replies, he probably doesn't know what you are talking about, explain yourself in the future)...

The D/4 rules applies to co-axials ONLY *rolls eyes at S_T*.

Anyway it roughly calculates how much 'travel' your piston needs to open to achieve full flow. You want to limit how far your piston can travel back to cut down on pilot volume (wasted air pretty much) but you don't want to cut down too much and limit your flow.

In barrel sealers we generally use D/2, which means barrel diameter divided by 2 gives us the maximum distance the piston should travel back.

Though in chamber sealers it's a different story depending on where abouts your pistons seals against the chamber in the tee. 1" travel is probably enough for the piston but I can't say for sure.

Haha I think you have the exact same "gauge, "T" , air inlet valve" assembly I have on my "1 gallon gun" down to the "T" litterally. Works good, and is compact, can't complain with that.

Thats pretty impressive if your breaking the cinder blocks with a POTATO. One question tho - What kind of cinder block? Post a pic of it if you can (pre carnage state) cause my last "big gun" was a coaxile of similar proportions to your "concrete breaker" gun and it had trouble breaking cinder blocks with anything but a piercing projectile (which it would almost leave 2 clean holes in a cinder block, just barely cracking the rest of it.) So i'm just wondering if I was shooting at a super reinforced cinderblock design, and your shooting at the standard 2 void cinder block. Thanks

Oh and partially the reason your gun has noticably more kick than w/e at just 30psi is because of your excess piston throw. It's allowing the piston to build up more momentum, and when the piston stops the momentum tranfers into who's ever holding it. If you don't believe me - shim your piston so it only travels 1" and you will notice a drop in recoil, but hardly a noticable drop (if at all) in projectile exit velocity.

MrCrowley wrote:In barrel sealers we generally use D/2, which means barrel diameter divided by 2 gives us the maximum distance the piston should travel back.

Though in chamber sealers it's a different story depending on where abouts your pistons seals against the chamber in the tee. 1" travel is probably enough for the piston but I can't say for sure.

Well with that kind of chamber seal it does need at least 2" of travel to fully expose the barrel port.

Using a fatter valve body and an unconventional design can give you a chamber sealer that has between d/4 and d/2 travel though.

That's why I said it depends on where abouts the piston seals, if the chamber extends all the way to the edge of the barrel port, then 1" might be enough as if it had 2" travel, all the air may have already been gone by the time it's fully open.

I'm not totally sure though, it would be interesting to know if anyone out there has some figures.

Not only are the D/4 nazis not afoot, they would be pwned anyway, because that looks like a chamber sealing valve!

We need more posters like you, cardman. First post is a finished chamber-sealing piston valve (if I am correct in assuming the valve is chamber-sealing). If it's not chamber sealing, I'd be interested in some pictures of the valve internals (I'd be interested anyways as well).

I know I already posted, but after you posted that diagram, I realized a few more things I liked:

1.) The simplicity of your design. It has been reduced to the purely critical, which I like. Not a lot of time has been spent fretting over how it looked. Also, equalization is uncomplicated and very effective between the pilot chamber and main chamber. Instead of working on some sort of one-way equalization flow through the piston, you slapped on a manually controlled external equalization system.

2.) You have really stepped away from the stereotypical chamber-sealer, like the Supah valve, in the simplicity of design and lack of aesthetic worries. Good job.